Chem. J. Chinese Universities ›› 2024, Vol. 45 ›› Issue (11): 20240382.doi: 10.7503/cjcu20240382

• Article • Previous Articles     Next Articles

Protein-Small Molecule Interaction Electrospray Ionization Mass Spectrometry Study of the Ubiquitin/Adenosine Triphoshate Couple over Temperature Variation

LIU Siying1, SU Wen1,2, ZHOU Zhongyan1, YANG Zhiyu1, PEI Huafu1, HE Zhiru1, WANG Na1,3(), YUE Lei1()   

  1. 1.College of Biology,State Key Laboratory of Chemo/Biosensing and Chemometrics,Hunan University,Changsha 410000,China
    2.College of Pharmacy,Shaoyang University,Shaoyang 422000,China
    3.School of Chemistry and Chemical Engineering,Hunan University of Science and Technology,Xiangtan 411101,China
  • Received:2024-08-07 Online:2024-11-10 Published:2024-09-04
  • Contact: YUE Lei E-mail:wna@hnust.edu.cn;yuelei@hnu.edu.cn
  • Supported by:
    Supported by the National Key Research and Development Program of China(No.2023YFF0613400), the National Natural Science Foundation of China(No.22174037), the Joint Funds of Natural Science Foundation of the Hunan Province, China(No.2023JJ50255) and the Project of Natural Science Foundation of Changsha, China(No.202269490128)

Abstract:

In this paper, protein-small molecule interaction electrospray ionization mass spectrometry(PSMI-ESI-MS) was used to study a model protein, ubiquitin(Ubi), and one of the most important bioactive small molecules, adenosine triphosphate(ATP) system. At room temperature, the electrospray mass spectra of the Ubi/ATP couple at the concentration ratio of 1 μmol/L∶50 μmol/L mainly showed charge states at +5, +6, and +7, corresponding well with the charge of Ubi in native state. ATP mainly formed 1∶1 and 1∶2(molar ratio) complexes with +5 and +6 ubiquitin while complexes with +7 was much less abundant, indicating that ubiquitin in lower charge state has a stronger binding affinity for ATP. Analysis of Ubi/ATP mass spectra at different ratios showed that there was no significant difference in the binding state at the concentration dimension. However, there was a significant difference in the charge distribution of Ubi and Ubi-ATP complexes at temperature variation. The calculated binding affinity increased with increasing temperature, indicating that the interaction between Ubi and ATP was enhanced after unfolding. Furthermore, Gibbs free energy of folded and unfolded Ubi indicated that the presence of ATP increased the energy required for unfolding, thereby enhancing the stability of ubiquitin. In this study, multi-dimensional information such as stoichiometric ratio, affinity, and Gibbs free energy were obtained based on electrospray mass spectrometry analysis of ubiquitin and ATP in the temperature dimension. It provides a general strategy for subsequent studies on protein-small molecule interactions.

Key words: Electrospray ionization mass spectrometry, Ubiquitin, Adenosine triphosphate, Protein-small molecule interaction

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